Ultrasonic imaging devices are widely used to make internal organs visible in hospitals. However, a catheter inside body cavities cannot be well seen due to sound attenuation and small reflection from the catheter. Many efforts have been made in this field.
U.S. Pat. No. 8,938,283 to Zentgraf et al, which is incorporated herein for reference, describes a technique capable of providing a 3D context for transesophogeal echocardiography data. It consists of a 3D tracking system and an ultrasonic imaging system. A position sensor is embedded inside the ultrasonic probe. U.S. Pat. No. 8,870,779 to Altmann et al, which is incorporated herein for reference, describes a medical imaging system for imaging a patient's body. The system includes a catheter comprising an electrical position sensor and an ultrasonic imaging sensor. In both systems, the position sensors are different from the present invention.
U.S. Pat. No. 8,412,307 to Willis et al and U.S. Pat. No. 6,216,027 to Willis et al, which is incorporated herein for reference, describes an invention to use several ultrasonic transducers inside a heart to establish a fixed 3D coordination system. The system is used in the heart to help the physician guide mapping catheters. U.S. Pat. No. 6,773,402 to Govari et al, which is incorporated herein for reference, describes an invention to use a series of ultrasonic transducers embedded along a catheter for 3D imaging of a heart. The apparatus is for mapping a surface of a cavity within a body. U.S. Pat. No. 6,773,402 to Govari et al, which is incorporated herein for reference, describes an ultrasonic catheter having at least two ultrasonic arrays. The device provides an outline of the heart chamber. Each of the foresaid catheter systems works alone and does not combine a base imaging system as in the present invention.
U.S. Pat. No. 6,515,657 to Zanelli et al, which is incorporated herein for reference, describes an ultrasound imaging system superimposes sectional views created from volumetric ultrasound data and the location data for an intervention device. However, it does not provide details on what kind of catheter to use or whether an active excitation to apply to it.
U.S. Pat. No. 5,343,865 to Gardineer et al, which is incorporated herein for reference, describes an apparatus and method for locating an interventional medical device with an ultrasound color imaging system. The catheter/needle is vibrating and its position is shown as a color image on the conventional color ultrasound display. The present invention takes use of active ultrasound signals instead of vibrations.
U.S. Pat. No. 8,303,509 to Webler et al, which is incorporated herein for reference, describes a catheter having a spherical distal tip to improve its ultrasonic image. Here the passive echo is different from an active signal in the present invention.
U.S. Pat. No. 5,797,849 to Vesely et al, which is incorporated herein for reference, describes a method for carrying out a medical procedure using a 3-D tracking and imaging system. A number of pairs of ultrasonic transducers are employed to track the position of a surgical instrument. The real-time position is provided for an imaging modality system such as a fluoroscope, MRI, CT or ultrasonic device. However, it does not teach details whether and how to configure the modality system.
U.S. Pat. No. 8,900,155 to Ridley et al, which is incorporated herein for reference, describes a method to use an ultrasound catheter with sterile seal to generate the virtual catheter overlay on a sonogram. Since the focus plane of sonogram has some thickness, the actual 3D position of the catheter cannot be easily indicated.
U.S. Pat. No. 5,515,853 to Smith et al, which is incorporated herein for reference, describes a 3-D ultrasound tracking system based on triangulation. However, using a series of transducers contained in a chest harness around a patient looks not a convenient setup for a surgery procedure.
Although many methods have been developed, it remains challenging to find a simple and suitable solution in tracking the catheter position inside body. For example, some physician employ ultrasonic device to assist the procedure of Transcatheter Aortic Valve Implantation (TAVI) to remedy aortic stenosis. Although the nature aortic valve can show on the sonogram, the catheter and the replaceable new valve cannot be easily seen. Contrast dye needs be injected into heart to check both positions under fluoroscope. As we know, the X ray exposure and contrast dye are not good to human body. If a simple ultrasonic probe device can display both the nature valve and catheter on the echocardiography image, it will improve the TAVI procedure significantly.
A conventional ultrasonic probe detects sound reflection and scattering to generate sonographic imaging. However, for an object in a deep position such as a catheter tip, the passive reflected sound signal is weak so its image is not clear. The present invention creates active sound signals from such a deep object so it is easier to be detected by the probe transducers.
On the other hand, the conventional ultrasonic probe can only detect objects within its focus plane of limited thickness. It is a great benefit if it can detect the catheter object earlier when it is far away from the focus plane. To accomplish this, the present invention employs 4 separate ultrasonic sensors located at each corner inside the probe head.